Model help:TopoFlow-Infiltration-Richards 1D

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The CSDMS Help System

TopoFlow-Infiltration-Richards 1D

This module is the infiltration process component (Richards 1D method) for a D8-based, spatial hydrologic model.

Model introduction

This process component is part of a spatially-distributed hydrologic model called TopoFlow, but it can now be used as a stand-alone model.

Model parameters

Parameter Description Unit
Component status Enabled/Disabled
Input directory -
Output directory -
Site prefix file prefix for the study site -
Case prefix file prefix for the model scenario -
Number of steps -
Number of soil layers -
Time step time step for infiltration process sec
Parameter Description Unit
K_sat type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
K_sat sat. hydraulic conductivity m / s
K_init type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
K_init init. hydraulic conductivity m / s
theta_sat type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
theta_sat sat. soil water content -
theta_init type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
theta_init init. soil water content -
theta_r type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
theta_r residual soil water content -
psi_B type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
psi_B bubbling pressure head m
psi_A type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
psi_A pressure head offset parameter m
lambda type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
lambda pore-size distribution parameter -
c type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
c trans. Brooks-Corey curvature -
dz vertical distance between nodes m
nz number of vertical nodes in layer -
Closet soil_type Closet standard soil_type -
Parameter Description Unit
K_sat type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
K_sat sat. hydraulic conductivity m / s
K_init type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
K_init init. hydraulic conductivity m / s
theta_sat type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
theta_sat sat. soil water content -
theta_init type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
theta_init init. soil water content -
theta_r type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
theta_r residual soil water content -
psi_B type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
psi_B bubbling pressure head m
psi_A type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
psi_A pressure head offset parameter m
lambda type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
lambda pore-size distribution parameter -
c type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
c trans. Brooks-Corey curvature -
dz vertical distance between nodes m
nz number of vertical nodes in layer -
Closet soil_type Closet standard soil_type -


Parameter Description Unit
K_sat type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
K_sat sat. hydraulic conductivity m / s
K_init type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
K_init init. hydraulic conductivity m / s
theta_sat type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
theta_sat sat. soil water content -
theta_init type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
theta_init init. soil water content -
theta_r type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
theta_r residual soil water content -
psi_B type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
psi_B bubbling pressure head m
psi_A type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
psi_A pressure head offset parameter m
lambda type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
lambda pore-size distribution parameter -
c type allowed input types (Scale/Grid/Time_series/Grid_Sequence) -
c trans. Brooks-Corey curvature -
dz vertical distance between nodes m
nz number of vertical nodes in layer -
Closet soil_type Closet standard soil_type -
Parameter Description Unit
Save grid timestep time interval between saved grid sec
Save v0 grids toggle option to save grids of infil.rate (at surf) -
Save v0 grids file filename for grid stack of v0 m / s
Save I grids toggle option to save grids of cumul. infil.depth -
Save I grids file filename for grid stack of I m
Save q0 grids toggle option to save grids of soil water content (at surf) -
Save q0 grids file filename for grid stack of q0 -
Save Zw grids toggle option to save grids of depth to wetting front -
Save Zw grids file filename for grid stack of Zw m
Parameter Description Unit
Save pixels timestep time interval between time series value sec
Save v0 pixels toggle option to save time series of infil.rate (at surf) -
Save v0 pixels file filename for time series of v0 m / s
Save I pixels toggle option to save time series of cumul. infil.depth -
Save I pixels file filename for time series of I m
Save q0 pixels toggle option to save time series of soil water content (at surf) -
Save q0 pixels file filename for time series of q0 -
Save Zw grids toggle option to save grids of depth to wetting front -
Save Zw grids file filename for grid stack of Zw m
Parameter Description Unit
Save profile timestep time interval between 1D profiles sec
Save q profiles toggle option to 1D profile of soil water content -
Save q profiles file filename for 1D profile of theta -
Save p profiles toggle option to 1D profile of pressure head -
Save p profiles file filename for 1D profile of psi m
Save K profiles toggle option to save 1D profile of hydr. conductivity -
Save K profiles file filename for 1D profile of K m / s
Save v profiles toggle option to save 1D profile of vert. flow rate -
Save v profiles file filename for 1D profile of v m / s

Uses ports

• Meteorology
• Snow (Snowmelt)
• Evap (Evaporation)
• Satzone (Subsurface flow in saturated zone)
• Channels (surface water flow in a network of channels)

Provides ports

• Infil (Infiltration)
• Configure (tabbed dialog GUI to change settings)
• Run (only if used as the Driver)

Main equations

  • Darcy's law for vertical flow rate
[math]\displaystyle{ v= K \ast \left ( 1 - \Psi\right) }[/math] (1)
  • Conservation of mass, with source/sink term J (subscripts are partial derivatives)
[math]\displaystyle{ v_{z}= J - \theta_{t} }[/math] (2)
  • Effective saturation or scaled water content (in [0,1]. Equals 0 when θ = θr. Equals 1 when θ = θs.))
[math]\displaystyle{ \Theta_{e}= \left ( \theta - \theta_{r}\right) / \left ( \theta_{s} - \theta_{r} \right) }[/math] (3)
  • Hydraulic conductivity
[math]\displaystyle{ K= K_{s} \ast \Theta_{e}^{\frac{\eta}{\lambda}} }[/math] (4)
  • Pressure head
[math]\displaystyle{ \Psi= \Psi_{B} \left ( \Theta_{e}^{\frac{-c}{\lambda}} - 1 \right)^{\frac{1}{c}} - \Psi_{A} }[/math] (5)

Notes

Notes on Input Parameters

For each variable, you may choose from the droplist of data types. For the "Scalar" data type, enter a numeric value with the units indicated in the dialog. For the other data types, enter a filename. Values in files must also use the indicated units.

Single grids and grid sequences are assumed to be stored as RTG and RTS files, respectively. Time series are assumed to be stored as text files, with one value per line. For a time series or grid sequence, the time between values must coincide with the timestep provided.

The current version allows up to 3 different soil layers, each with its own soil properties and number of vertical nodes. The soil layer number is indicated at the top of the dialog and you use the Next and Back buttons to view settings for the various layers.

Notes on the Equations

All variables and their units can be seen by expanding the Nomenclature section above.

These equations are used to compute the time evolution of 1D (vertical, subsurface) profiles for (1) soil moisture, θ, (2) pressure head, ψ, (3) hydraulic conductivity, K and (4) vertical flow rate, v. TopoFlow solves these equations separately to get time-evolving profiles for every grid cell in a DEM. The result is a 3D grid for each of these four variables that spans the unsaturated zone. The third equation above just defines a variable that is used in the 4th and 5th equations, so the coupled set constitutes 4 equations to be solved for 4 unknowns. These equations can be combined into one nonlinear, parabolic, second-order PDE (partial differential equation) known as the one-dimensional Richards' equation.

The infiltration rate is simply the vertical flow rate at the ground surface, denoted by v0.

Soil moisture is simply another term for the water content in the case where the porous medium is a soil.

Subscripts in the first two equations indicate partial derivatives with respect to the vertical coordinate, z. Note that z is the vertical distance below the ground surface, in meters.

More information on how soil is modeled in TopoFlow along with published soil property tables can be found on this soil properties page.

Two other, simpler methods for modeling infiltration are described on the help pages for the Green-Ampt method and the Smith-Parlange 3-parameter method.

Examples

An example run with input parameters, BLD files, as well as a figure / movie of the output

Follow the next steps to include images / movies of simulations:

See also: Help:Images or Help:Movies

Developer(s)

Scott Peckham

References

Dingman, S.L. (2002) Physical Hydrology, 2nd ed., Prentice-Hall, Upper Saddle River, New Jersey, 646 pp.

Smith, R.E. (2002) Infiltration Theory for Hydrologic Applications, Water Resources Monograph 15, AGU, 212 pp.

Links

Related Help Pages

Model Metadata